Tubes and bottles made from thin-walled plastic or plastic laminated material are used for packaging of, for example, creams, ointments and various other viscous chemical/engineering preparations. Swedish Patent Application 8800548-3 describes an end-piece and a method for manufacturing tubes or bottles by butt-welding an end-piece in both ends of a tubular-shaped body portion of thin-walled plastic or laminated plastic material.
The advantage of manufacturing tubes or bottles in this way is that the need to transport bulky empty containers over long distances is avoided. Accordingly the method allows the private packager to produce his own tubes or bottles without comprehensive equipment.
The tube or bottle produced according to the above method can be filled with its product via its opening, after which a cap is affixed over the opening with the aid of, for example, screw threads.
In many cases, however, it is desirable to provide a container which has been sealed in a controlled environment so that the customer can confirm that the packaging is unopened. This results in enhanced quality, both for the packaging and its contents.
During production of such a sealed container it is advantageous that filling with the product occurs between the fitting of the first end-piece, preferably tubularly formed, and the second end-piece.
In the method according to said Swedish Patent Application 8800548.3 tubular-shaped body portions are located on a rotary indexing table for movement between various stations. At one station each end-piece is introduced into the upper end of a corresponding body portion by a piston to an intermediate position where it partially projects into the body portion. This partially assembled work piece is then moved to the next station where heating energy is supplied to the circumferential end region of the tube and intersecting region of the end piece. Once a temperature is attained at which the material is sufficiently soft, the work piece is advanced to the subsequent station where a piston is reapplied to push the end piece to its terminal position. Rapid cooling of the welding site is then achieved by means of passages within the piston for a cooling fluid.
Up until recently it has proved impossible to apply the end-piece with the piston in situ during heating since the rim of the end-piece upon which the piston acts is subjected to heating to between 300.degree. C.-500.degree. C., thereby softening the material and causing it to adhere to the piston.
A partial solution to this problem is described in PCT/SE/91/00124 claiming priority from SE 9001086-9, filed 26 Mar., 1990, both of which were published after the filing date of the present application. Said documents relate to a method and a device for controlling the temperature of a container end portion during manufacture. An end-piece is placed in a defined intermediate position where it partially projects into the open end of a tubular body. Warm gas is supplied to the body portion end region and the end of the outwardly projecting portion of the end piece in order to soften the material in these portions. The end-piece is then pushed to its terminal position in the tubular body at the same time that a cooling gas is supplied to the transverse wall of the end-piece, thereby preventing the pushing means adhering to the transverse wall.